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Message-ID: <ZcVtzJvJCRV5OLM-@slm.duckdns.org>
Date: Thu, 8 Feb 2024 14:11:56 -1000
From: Tejun Heo <tj@...nel.org>
To: Marek Szyprowski <m.szyprowski@...sung.com>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>, linux-kernel@...r.kernel.org,
Lai Jiangshan <jiangshanlai@...il.com>
Subject: [PATCH 1/2 wq/for-6.9] workqueue: Implement
workqueue_set_min_active()
Since 5797b1c18919 ("workqueue: Implement system-wide nr_active enforcement
for unbound workqueues"), unbound workqueues have separate min_active which
sets the number of interdependent work items that can be handled. This value
is currently initialized to WQ_DFL_MIN_ACTIVE which is 8. This isn't high
enough for some users, let's add an interface to adjust the setting.
Signed-off-by: Tejun Heo <tj@...nel.org>
---
include/linux/workqueue.h | 2 ++
kernel/workqueue.c | 27 +++++++++++++++++++++++++++
2 files changed, 29 insertions(+)
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -553,6 +553,8 @@ extern bool flush_rcu_work(struct rcu_wo
extern void workqueue_set_max_active(struct workqueue_struct *wq,
int max_active);
+extern void workqueue_set_min_active(struct workqueue_struct *wq,
+ int min_active);
extern struct work_struct *current_work(void);
extern bool current_is_workqueue_rescuer(void);
extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -5627,6 +5627,33 @@ void workqueue_set_max_active(struct wor
EXPORT_SYMBOL_GPL(workqueue_set_max_active);
/**
+ * workqueue_set_min_active - adjust min_active of an unbound workqueue
+ * @wq: target unbound workqueue
+ * @min_active: new min_active value
+ *
+ * Set min_active of an unbound workqueue. Unlike other types of workqueues, an
+ * unbound workqueue is not guaranteed to be able to process max_active
+ * interdependent work items. Instead, an unbound workqueue is guaranteed to be
+ * able to process min_active number of interdependent work items which is
+ * %WQ_DFL_MIN_ACTIVE by default.
+ *
+ * Use this function to adjust the min_active value between 0 and the current
+ * max_active.
+ */
+void workqueue_set_min_active(struct workqueue_struct *wq, int min_active)
+{
+ /* min_active is only meaningful for non-ordered unbound workqueues */
+ if (WARN_ON((wq->flags & (WQ_BH | WQ_UNBOUND | __WQ_ORDERED)) !=
+ WQ_UNBOUND))
+ return;
+
+ mutex_lock(&wq->mutex);
+ wq->saved_min_active = clamp(min_active, 0, wq->saved_max_active);
+ wq_adjust_max_active(wq);
+ mutex_unlock(&wq->mutex);
+}
+
+/**
* current_work - retrieve %current task's work struct
*
* Determine if %current task is a workqueue worker and what it's working on.
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